Mobility Anchor issue between 9800 and 5508 Control Path Down

[pgill.uwo@gmail.com]

My environment :
Foreign 9800 - Code version tested - 17.6.4 and 17.3.6

Anchor 5508 - 8.8.130 and 8.5.X

I am having issues while creating tunnel between 9800 ( foreign ) and 5508 ( Anchor ). WLC IPs can ping each other ( data path is up ) but control path is down. Error logs:

2023/01/23 13:32:47.569357 {mobilityd_R0-0}{1}: [mm-dtls] [19101]: (note): Peer IP: 149.x.x.x Port: 16666 DTLS_UNPLUMB: Key unplumb msg sent to FMAN
2023/01/23 13:32:47.569365 {mobilityd_R0-0}{1}: [mm-dtls] [19101]: (note): Peer IP: 149.x.x.x Port: 16666 DTLS_CLEAR_KEY: DTLS keys cleared from MNC and FMAN
2023/01/23 13:32:47.569919 {mobilityd_R0-0}{1}: [mm-dtls] [19101]: (note): Peer IP: 149.x.x.x Port: 16666, Local IP: 157.x.x.x Port: 16666 DTLS_FMAN_ACKNACK: Key unplumb FMAN ACK handled.DTLS connection status: Disabled
2023/01/23 13:32:52.865782 {mobilityd_R0-0}{1}: [mm-dtls] [19101]: (note): Peer IP: 149.x.x.x Port: 16666, Local IP: 157.x.x.x Port: 16666 DTLS_CONNECT: DTLS connection initiated
2023/01/23 13:34:47.570926 {mobilityd_R0-0}{1}: [mm-dtls] [19101]: (note): Peer IP: 149.x.x.x Port: 16666, Local IP: 157.x.x.x Port: 16666 DTLS session not established for 4 intervals. Keepalive status 0. Close DTLS connection.
2023/01/23 13:34:47.571300 {mobilityd_R0-0}{1}: [ewlc-dtls-sess] [19101]: (note): Remote Host: 149.x.x.x [16666] DTLS session destroy

Appreciate help. thanks

[balaji.bandi]

I am sure you may have checked the version requirement of the IRCM version.

is this controller behind NAT?

https://www.cisco.com/c/en/us/td/docs/wireless/controller/9800/17-1/config-guide/b_wl_17_11_cg/b_wl_17_11_cg_chapter_010000001.html

[pgill.uwo@gmail.com · Accepted solution]

Thanks for the recommendations. After much digging we found Mobility group was wrong on the Anchor controller. After it was fixed tunnels came up lightening. 
thanks again.