You have to use the matrix at the bottom where correct lient and server config are linked:https://docs.opnsense.org/manual/how-tos/ipsec-rw.htmlI tested it with Ubuntu 18.04
Dec 12 10:19:08 my-ubuntu-20.04-pc charon-nm: 04[CFG] received initiate for NetworkManager connection WV VPN 2Dec 12 10:19:08 my-ubuntu-20.04-pc charon-nm: 04[CFG] using CA certificate, gateway identity '192.168.1.181'Dec 12 10:19:08 my-ubuntu-20.04-pc charon-nm: 04[IKE] initiating IKE_SA WV VPN 2[14] to 192.168.1.181Dec 12 10:19:08 my-ubuntu-20.04-pc charon-nm: 04[ENC] generating IKE_SA_INIT request 0 [ SA KE No N(NATD_S_IP) N(NATD_D_IP) N(FRAG_SUP) N(HASH_ALG) N(REDIR_SUP) ]Dec 12 10:19:08 my-ubuntu-20.04-pc charon-nm: 04[NET] sending packet: from 192.168.1.88[53337] to 192.168.1.181[500] (936 bytes)Dec 12 10:19:08 my-ubuntu-20.04-pc NetworkManager[1360]: <info> [1607768348.5185] vpn-connection[0x560217f50130,7723a298-6e57-46bd-981f-4359fa9b7bc8,"WV VPN 2",0]: VPN plugin: state changed: starting (3)Dec 12 10:19:08 my-ubuntu-20.04-pc charon-nm: 05[NET] received packet: from 192.168.1.181[500] to 192.168.1.88[53337] (38 bytes)Dec 12 10:19:08 my-ubuntu-20.04-pc charon-nm: 05[ENC] parsed IKE_SA_INIT response 0 [ N(INVAL_KE) ]Dec 12 10:19:08 my-ubuntu-20.04-pc charon-nm: 05[IKE] peer didn't accept DH group ECP_256, it requested MODP_2048Dec 12 10:19:08 my-ubuntu-20.04-pc charon-nm: 05[IKE] initiating IKE_SA WV VPN 2[14] to 192.168.1.181Dec 12 10:19:08 my-ubuntu-20.04-pc charon-nm: 05[ENC] generating IKE_SA_INIT request 0 [ SA KE No N(NATD_S_IP) N(NATD_D_IP) N(FRAG_SUP) N(HASH_ALG) N(REDIR_SUP) ]Dec 12 10:19:08 my-ubuntu-20.04-pc charon-nm: 05[NET] sending packet: from 192.168.1.88[53337] to 192.168.1.181[500] (1128 bytes)Dec 12 10:19:08 my-ubuntu-20.04-pc charon-nm: 14[NET] received packet: from 192.168.1.181[500] to 192.168.1.88[53337] (557 bytes)Dec 12 10:19:08 my-ubuntu-20.04-pc charon-nm: 14[ENC] parsed IKE_SA_INIT response 0 [ SA KE No N(NATD_S_IP) N(NATD_D_IP) CERTREQ N(FRAG_SUP) N(HASH_ALG) N(CHDLESS_SUP) N(MULT_AUTH) ]Dec 12 10:19:08 my-ubuntu-20.04-pc charon-nm: 14[CFG] selected proposal: IKE:AES_CBC_256/HMAC_SHA2_256_128/PRF_HMAC_SHA2_256/MODP_2048Dec 12 10:19:08 my-ubuntu-20.04-pc charon-nm: 14[IKE] received cert request for "C=GB, ST=West Midlands, L=<redacted>, O=<redacted>, E=<redacted>, CN=opnsense-ca-root"Dec 12 10:19:08 my-ubuntu-20.04-pc charon-nm: 14[IKE] received 3 cert requests for an unknown caDec 12 10:19:08 my-ubuntu-20.04-pc charon-nm: 14[IKE] sending cert request for "C=GB, ST=West Midlands, L=<redacted>, O=<redacted>, E=<redacted>, CN=opnsense-ca-root"Dec 12 10:19:08 my-ubuntu-20.04-pc charon-nm: 14[IKE] establishing CHILD_SA WV VPN 2{13}Dec 12 10:19:08 my-ubuntu-20.04-pc charon-nm: 14[ENC] generating IKE_AUTH request 1 [ IDi N(INIT_CONTACT) CERTREQ CPRQ(ADDR ADDR6 DNS NBNS DNS6) SA TSi TSr N(MOBIKE_SUP) N(ADD_4_ADDR) N(ADD_4_ADDR) N(ADD_6_ADDR) N(MULT_AUTH) N(EAP_ONLY) N(MSG_ID_SYN_SUP) ]Dec 12 10:19:08 my-ubuntu-20.04-pc charon-nm: 14[NET] sending packet: from 192.168.1.88[53150] to 192.168.1.181[4500] (464 bytes)Dec 12 10:19:08 my-ubuntu-20.04-pc charon-nm: 08[NET] received packet: from 192.168.1.181[4500] to 192.168.1.88[53150] (1236 bytes)Dec 12 10:19:08 my-ubuntu-20.04-pc charon-nm: 08[ENC] parsed IKE_AUTH response 1 [ EF(1/2) ]Dec 12 10:19:08 my-ubuntu-20.04-pc charon-nm: 08[ENC] received fragment #1 of 2, waiting for complete IKE messageDec 12 10:19:08 my-ubuntu-20.04-pc charon-nm: 01[NET] received packet: from 192.168.1.181[4500] to 192.168.1.88[53150] (756 bytes)Dec 12 10:19:08 my-ubuntu-20.04-pc charon-nm: 01[ENC] parsed IKE_AUTH response 1 [ EF(2/2) ]Dec 12 10:19:08 my-ubuntu-20.04-pc charon-nm: 01[ENC] received fragment #2 of 2, reassembled fragmented IKE message (1920 bytes)Dec 12 10:19:08 my-ubuntu-20.04-pc charon-nm: 01[ENC] parsed IKE_AUTH response 1 [ IDr CERT AUTH EAP/REQ/ID ]Dec 12 10:19:08 my-ubuntu-20.04-pc charon-nm: 01[IKE] received end entity cert "C=GB, ST=West Midlands, L=<redacted>, O=<redacted>, E=<redacted>, CN=wv.xxx.com, subjectAltName=IP:192.168.1.181"Dec 12 10:19:08 my-ubuntu-20.04-pc charon-nm: 01[CFG] using certificate "C=GB, ST=West Midlands, L=<redacted>, O=<redacted>, E=<redacted>, CN=wv.xxx.com, subjectAltName=IP:192.168.1.181"Dec 12 10:19:08 my-ubuntu-20.04-pc charon-nm: 01[CFG] using trusted ca certificate "C=GB, ST=West Midlands, L=<redacted>, O=<redacted>, E=<redacted>, CN=opnsense-ca-root"Dec 12 10:19:08 my-ubuntu-20.04-pc charon-nm: 01[CFG] checking certificate status of "C=GB, ST=West Midlands, L=<redacted>, O=<redacted>, E=<redacted>, CN=wv.xxx.com, subjectAltName=IP:192.168.1.181"Dec 12 10:19:08 my-ubuntu-20.04-pc charon-nm: 01[CFG] certificate status is not availableDec 12 10:19:08 my-ubuntu-20.04-pc charon-nm: 01[CFG] reached self-signed root ca with a path length of 0Dec 12 10:19:08 my-ubuntu-20.04-pc charon-nm: 01[IKE] authentication of 'C=GB, ST=West Midlands, L=<redacted>, O=<redacted>, E=<redacted>, CN=wv.xxx.com, subjectAltName=IP:192.168.1.181' with RSA_EMSA_PKCS1_SHA2_256 successfulDec 12 10:19:08 my-ubuntu-20.04-pc charon-nm: 01[IKE] server requested EAP_IDENTITY (id 0x00), sending 'expert'Dec 12 10:19:08 my-ubuntu-20.04-pc charon-nm: 01[ENC] generating IKE_AUTH request 2 [ EAP/RES/ID ]Dec 12 10:19:08 my-ubuntu-20.04-pc charon-nm: 01[NET] sending packet: from 192.168.1.88[53150] to 192.168.1.181[4500] (96 bytes)Dec 12 10:19:08 my-ubuntu-20.04-pc charon-nm: 10[NET] received packet: from 192.168.1.181[4500] to 192.168.1.88[53150] (112 bytes)Dec 12 10:19:08 my-ubuntu-20.04-pc charon-nm: 10[ENC] parsed IKE_AUTH response 2 [ EAP/REQ/MSCHAPV2 ]Dec 12 10:19:08 my-ubuntu-20.04-pc charon-nm: 10[IKE] server requested EAP_MSCHAPV2 authentication (id 0x87)Dec 12 10:19:08 my-ubuntu-20.04-pc charon-nm: 10[ENC] generating IKE_AUTH request 3 [ EAP/RES/MSCHAPV2 ]Dec 12 10:19:08 my-ubuntu-20.04-pc charon-nm: 10[NET] sending packet: from 192.168.1.88[53150] to 192.168.1.181[4500] (144 bytes)Dec 12 10:19:10 my-ubuntu-20.04-pc charon-nm: 16[NET] received packet: from 192.168.1.181[4500] to 192.168.1.88[53150] (128 bytes)Dec 12 10:19:10 my-ubuntu-20.04-pc charon-nm: 16[ENC] parsed IKE_AUTH response 3 [ EAP/REQ/MSCHAPV2 ]Dec 12 10:19:10 my-ubuntu-20.04-pc charon-nm: 16[IKE] EAP-MS-CHAPv2 failed with error ERROR_AUTHENTICATION_FAILURE: '(null)'Dec 12 10:19:10 my-ubuntu-20.04-pc charon-nm: 16[IKE] EAP_MSCHAPV2 method failed
2020-12-12T10:19:10 charon[10631]: 04[NET] <con1|2> sending packet: from 192.168.1.181[4500] to 192.168.1.88[53150] (80 bytes)2020-12-12T10:19:10 charon[10631]: 04[ENC] <con1|2> generating INFORMATIONAL response 4 [ N(AUTH_FAILED) ]2020-12-12T10:19:10 charon[10631]: 04[ENC] <con1|2> parsed INFORMATIONAL request 4 [ N(AUTH_FAILED) ]2020-12-12T10:19:10 charon[10631]: 04[NET] <con1|2> received packet: from 192.168.1.88[53150] to 192.168.1.181[4500] (80 bytes)2020-12-12T10:19:10 charon[10631]: 04[NET] <con1|2> sending packet: from 192.168.1.181[4500] to 192.168.1.88[53150] (128 bytes)2020-12-12T10:19:10 charon[10631]: 04[ENC] <con1|2> generating IKE_AUTH response 3 [ EAP/REQ/MSCHAPV2 ]2020-12-12T10:19:08 charon[10631]: 04[IKE] <con1|2> EAP-MS-CHAPv2 verification failed, retry (1)2020-12-12T10:19:08 charon[10631]: 04[IKE] <con1|2> no EAP key found for hosts 'C=GB, ST=West Midlands, L=<redacted>, O=<redacted>, E=<redacted>, CN=<redacted>, subjectAltName=IP:192.168.1.181' - 'expert'2020-12-12T10:19:08 charon[10631]: 04[ENC] <con1|2> parsed IKE_AUTH request 3 [ EAP/RES/MSCHAPV2 ]2020-12-12T10:19:08 charon[10631]: 04[NET] <con1|2> received packet: from 192.168.1.88[53150] to 192.168.1.181[4500] (144 bytes)2020-12-12T10:19:08 charon[10631]: 04[NET] <con1|2> sending packet: from 192.168.1.181[4500] to 192.168.1.88[53150] (112 bytes)2020-12-12T10:19:08 charon[10631]: 04[ENC] <con1|2> generating IKE_AUTH response 2 [ EAP/REQ/MSCHAPV2 ]2020-12-12T10:19:08 charon[10631]: 04[IKE] <con1|2> initiating EAP_MSCHAPV2 method (id 0x87)2020-12-12T10:19:08 charon[10631]: 04[IKE] <con1|2> received EAP identity 'expert'2020-12-12T10:19:08 charon[10631]: 04[ENC] <con1|2> parsed IKE_AUTH request 2 [ EAP/RES/ID ]